Table 2: Epidemiological evidence about the relationship between silicon-derived compounds and autoimmune diseases.

CompoundresultsReference

A review of the medical records of individuals reported to the Michigan Silicosis Surveillance system from 1985 to 2006 showed that individuals with silicosis had a two- to eightfold risk of developing RA and SLE with a greater than 24-fold risk for scleroderma and ANCA vasculitis. [47]
In a retrospective report of patients attending the Ben Aknoun Hospital (Argelia), 9 cases of autoimmune diseases with occupational exposure to silica were found (7 Si, 4 SSc, 3 RA, 1 SLE, 1 SS). [48]
A case control study (577 cases of RA and 659 matched controls) showed that silicaexposure combined with smoking among men is associated with an increased risk of developing anti-CCP positive RA (OR: 7.36). [49]
Two out of 78 workers exposed to silica who were evaluated presented positive levels of RF. [50]
Association study including 276 male with RA and 276 controls. Of the 276 males cases in this study, 41 were exposed to silica. This exposure increased the 2.2 the risk of RA regardless of age, residential areas and smoking. [51]
Case report of a 63-year-old man exposed to silica for 30 years and diagnosed with leukocytoclastic vasculitis. [52]
Case report of a 72-year old, a retired dental technician exposed to silica, with a rare case of SS. [53]
SilicaCase report of a 39-year-old painter who developed severe seropositive RA. Additional investigation revealed silicosis manifested exclusively in the mediastinal lymph node with no pulmonary abnormality. [54]
An analysis using death certificates from 27 states in the USA showed an association between potential occupational crystalline silica exposure and mortality due to RA. [55]
Case report of a 28-year-old female dental technician showed a history of exposure to ceramic silica and symptoms characteristic of RA with lung interstitial disorder. The patient presented elevated RF and HLA risk haplotypes (HLA-A2-A31, HLA-B51-B18, and HLA-DR3-DR11). [56]
A report of two cases of coexistence of pulmonary silicosis and SLE in two men exposed to silica for 20 years. [57]
In a morbidity and mortality analysis in a cohort of 4,626 silica-exposed workers in the industrial sand industry, RA was seen to be one of the main causes of death in this cohort (SMR: 4.36). [58]
A case-control study to compare the occupational background of 31 cases of biopsy proven vasculitis showed that silica exposure is more present in cases than controls. [59]
The report of a case-control study of sixty-five patients with ANCA-SVV and 65 matched control subjects. The results showed that silica dust exposure is associated with ANCA-SVV (OR: 4.6). [60]
In a study of 4,500 people in the town of Husavik, a relationship was found between sarcoidosis and exposure to crystallinesilica (OR: 13.2). In 8 cases in which sarcoidosis was found, 6 had been exposed (Iceland). [61]

A case series study where three groups of women were compared, the first one developed myositis after they received silicone implants (MASI), the second group was women with myositis but without silicone implants and thelast group was composedof healthy women with silicone implants. This study found that MASI patients have an increased frequency of HLA-DQA1 * 0102 allele. [62]
Out of a total of 813 individuals with silicone breast implants, ANAs were found in 244 (30%).[63]
SiliconeCase report of a 25 year-old female who at the age of 11 was diagnosed with Still's disease. At the age of 22, she underwent silicone breast implant surgery and presented with a transient lupus-like syndrome. Then, at 25 years of age she had a severe activation of Still's disease in association with a rupture of the implants. This case meets the criteria for ASIA syndrome.[64]
The impact of implant integrity on clinical symptoms and antibody status was assessed in 90 consecutive female patients with silicone breast implants. The results indicated that implant integrity has no major impact on rheumatic symptoms. [65]
A meta-analysis demonstrated that there was no evidence that breast implants were associated with a significant increase in the adjusted relative risk of connective-tissue diseases.[66]

RA: rheumatoid arthritis; SLE: systemic Lupus erythematosus; ANCA: anti-neutrophil cytoplasmic antibody; SI: silicosis; SSc: systemic sclerosis; SS: Sjogren syndrome; OR: odds ratio; RF: rheumatoid factor; SMR: standardized mortality ratio; SVV: small-vessel vasculitis; MASI: myositis after silicone implants; ASIA: autoimmune/inflammatory syndrome induced by adjuvants; ANAs: antinuclear antibodies.